Prior art is limited to prisms with fixed integral faces which cannot be revolved, including the following patents;
1. Collimating System, U.S. Pat. No. 2,405,960, Aug. 20, 1946, E. H. Land. This device passes a beam of light through a prism as means of collimating the beam. PA0 2. Luminous Flux Diverging Apparatus Using Prisms, Japan Pat. No. 119,260, Sept. 17, 1979, Kazuo Sanagi. This apparatus uses four unaligned prisms to concentrate a beam.